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    <title>Document</title>
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<script>
    var arr = [1,2,3,4,5];
    function avg(array) {//封装求平均值函数
        var len = arr.length;
        var sum = 0;
        for(var i = 0;i<len;i++){
            sum +=array[i];
        }
        return sum/len;
    }
    console.log(avg(arr));

</script>
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